bypass fuel regulator for carb. swap?

[z2o_what]

im swaping my '86 5.0 into a 4cyl. car and also changing it to carb.

i would like to use the stock fuel pump but have read negative comments about keeping it...but would i be safe to use a bypass fuel regulator instead of a standard???

this way i figure that it wouldn't be such a dramatic drop from 40 to 7 psi.

 

[86bluecobra]

why not just rip out old fuel lines and run new 3/8 aluminium tube. its easy i did it in my 86. then you have all the supply of fuel you need and you have it at the right pressure.

 

[z2o_what]

im assuming that 3/8 line is smaller than stock...so by running 3/8 line from the tank to the motor will restrict flow enough to run a carb without the use of a regulator???

 

[jrichker]

A word of warning on EFI to carb swaps: don’t expect to pass emissions in any state that does comprehensive smog inspections, because it won’t happen. You must know how to read electrical diagrams and wire circuits properly to do the swap. Don’t take shortcuts or cut corners in the fabrication of the electrical or mechanical assemblies. If you do NASCAR quality work, the car will look good, run good and be as reliable as a carb’d car can be. Take pride in a job done with excellence.

If you do the hack job that is common among folks who don’t understand electricity or computers and are doing the conversion because it is easier than dealing with the EFI system, the result will look like and run like road kill. Wiring harnesses chopped up and spliced together with electrical tape, loose and dangling hoses, fuel lines spliced together with 3 types of fittings speak of ignorance and sloppy workmanship. If you can't do it right, don't do it at all. I wouldn’t wish a car with that kind of workmanship off on my worst enemy...

Now that the rant is over, here’s some practical advice…

Do not use an EFI in tank fuel pump with a carb. You will never get the pressure/flow regulated properly. Either go full EFI or use a tank/fuel pump/fuel lines out of an 85 or earlier Stang. Fabricating your own setup is possible but there are some snags to overcome.

Do not attempt to leave the EFI in place in an attempt to control either the electric fuel pump or ignition. Doing so qualifies you for the “Road Kill Mechanics Award”.

If you try to use your current tank, you will need to pull the fuel pump out and fabricate a pickup tube & strainer sock to replace the fuel pump. Or you can have a sump fabricated and welded onto you existing tank. Many welding shops will not weld fuel tanks because of the dangers involved if the tank isn't purged properly.

You will need an external electric fuel pump unless you change the timing cover for one with the mechanical fuel pump mount on it. Since you seem to be determined to rip all the EFI wiring out, the computer controlled fuel pump won't work. You will need to add a relay & switch and wire in the existing inertia switch for an external low pressure electric fuel pump.

You will need to run some new fuel feed lines or braided hose. The 3/8" aluminum tubing works well, but you will need a flaring tool and bending springs to fabricate the lines. Braided hose is easy to run and route, but is much more expensive. It is about $3.50-$4.00 a foot plus the end fittings, which are $3-$4 each. Fabricating hose assembles can be difficult, but anyplace that makes hydraulic hoses can do it for you for an extra charge. See http://www.amazonhose.com for more information.

While you are at the electrical part, you'll need a Durspark or similar ignition system. The EFI ignition depends on the EFI sensors to advance the spark. Rip out the TPS and MAP/Baro sensors and the computer will have no idea of the proper ignition timing for best performance. Running a fixed timing setting is only for test purposes or for a race track only car. Don't try it on the street: the results will not be nearly as good as a properly setup Durspark or equal. Crane makes a really nice distributor for non-EFI applications. See http://www.cranecams.com/index.php?show=browseParts&lvl=4&prt=127 for more information.

 

[z2o_what]

all that i wanted to know was if it would be better to use a bypass regulator than a standard. i didn't need a lecture.

and, i never said that i was "ripping" the wiring out of the car...and if i need to the MAP sensor i'll just run a vac. to it and see what happens.

 

[jrichker]

all that i wanted to know was if it would be better to use a bypass regulator than a standard. i didn't need a lecture.

and, i never said that i was "ripping" the wiring out of the car...and if i need to the MAP sensor i'll just run a vac. to it and see what happens.

I must have hit a nerve here...Obliviously you got offended and didn't read closely past the second paragraph. Too bad, there is some good advice there.

Don’t take shortcuts or cut corners in the fabrication of the electrical or mechanical assemblies. If you do NASCAR quality work, the car will look good, run good and be as reliable as a carb’d car can be. Take pride in a job done with excellence."

I stand by what I said. No exceptions, no apologies.

 

[joel5.0]

all that i wanted to know was if it would be better to use a bypass regulator than a standard. i didn't need a lecture.

and, i never said that i was "ripping" the wiring out of the car...and if i need to the MAP sensor i'll just run a vac. to it and see what happens.

Z20_what;

Jrichker is simply trying to give you good advice, nothing to feel ashamed or angry about...he's trying to help you!...(the words "Thank You" come to mind)

Regarding your original question, keeping the original high pressure pump is a no-no. If you don't want to mess with fuel lines, sumped tanks, etc....the other option would be to replace your hi-press in-tank pump for a Taurus '88 CFI in-tank pump (will bring pressure down to 19-23 PSI), keep the OEM fuel lines and yes....use an adjustable bypass regulator (see pic):

That's the setup I've had for 13 yrs. now and no problems.....but you need to replace the hi-pressure fuel pump. GL

 

[rd]

Good stuff here, anyone else have experience with the low pressure in tank pump?

I was thinking that the lp in tank route would be a good one, but did not know of a suitable pump.

I am also skeptical of using a Holley or Aeromotive in line with the suction line run out of the top of the tank. I have heard people say it works, but it seems like it would risk cavitation at launches, with the fuel going to the rear of the tank, and they having to be pulled up to the top of the tank to go forward.

So far, a sump or fuel cell seems like the only good answer.

 

[MrKwik]

all that i wanted to know was if it would be better to use a bypass regulator than a standard. i didn't need a lecture.

and, i never said that i was "ripping" the wiring out of the car...and if i need to the MAP sensor i'll just run a vac. to it and see what happens.

I don't think he was lecturing you, he was offering good advice. If you want to be an ass about it though, I would say figure it out yourself and let us know how it turns out. Food for thought...... Maybe if alot of poeple that have done something tell you its a bad idea, it probably is.

To answer your question....3/8 line is not smaller than stock and no way would it cause enough of a restriction to run the EFI pump without a regulator. I actually believe that the stock lines are only 5/16". If doing away with EFI, you will want to change to an ignition system that isnt controlled by the computer. At the risk of lecturing, thats all I will say on the subject. I will let you run with it from there.